Friday, December 23, 2005

Pale Male vs. the Great Horned Owl

John Blakeman writes about Great Horned Owls:

Red-tails and great-horneds in the East, South, and Midwest, have a remarkable relationship, an ecological détente, as it were. Here's how it works (mostly and usually).

The crucial fact is that great horned owls don't build nests. They simply expropriate (read that as steal) existing ones. No one -- even if they could see at night -- will ever observe an owl bringing twigs to a nest site. Owls don't do that. For the great-horneds, they just perch themselves on an existing red-tail's nest in December or January and claim it. GHO's are larger and more muscular than red-tails, and at night, red-tails can see about as well as we can. Red-tails will intelligently abandon a nest claimed by a great horned owl. The hawks will frequently go just a short distance and build a new nest, sometimes even in the same woodlot, perhaps only a few hundred yards from the old nest.

At night, a great horned owl could easily drop down upon an incubating red-tail and have her for a midnight snack. Conversely, in broad daylight, when a female owl is hunkered down over her owlets, a red-tail could do a classic red-tail stoop, a dive, and take the head off the owl before it knew what hit her.

But these things seldom happen. There is, as I mentioned, an ecological détente, an understanding, that the owls will do their things at night, and the hawks theirs in daylight. By this arrangement, the owls find beautifully formed, existing nests to claim each December (long before the red-tails resume nesting activities). For the red-tails, they don't get killed by the larger, more aggressive owls. This is a raptorial version of MAD, Mutually Assured Destruction, the tenuous but effective arrangement between American and Soviet thermonuclear powers.

So far, there have been no MAD things in Central Park. So far, there has been only one ecological Super Power, the red-tailed hawks. But, are things changing? Has a new super power emerged? Great horned owls have apparently been seen in Central Park in previous years, but only for short, incidental periods of time. The owls have not persisted.

But might that change? I think it could. Great horned owls hunt for and kill the same prey as red-tails. They use exactly the same habitat, only at night instead of in the hawks' day-hunting periods. And clearly there is an abundance of available food in Central Park. Because they are nocturnal hunters, great-horneds aren't going to take many pigeons. But at night there will be a surfeit of rats that owls could thrive upon.
The recent CP residency of a single great horned owl could only mean one of two things, another temporary, incidental "I'm just passin' through" visit, or more ominously (or interestingly) an extended reconnoitering of the prospects for a permanent CP residency.

What if this bird really likes what it finds, as did Pale Male, lo, those many years ago? What if this is a male on the search for a new, unoccupied territory where he could set up a territory and try to attract a female? There is plenty of food, of course.
There are two impediments for a great-horned residency. The first -- as originally with Pale Male -- would be the disruptive abundance of all those giant two-legged animals in the park. Great horned owls, like rural red-tails, just don't like humans close to their perches or nests. But the red-tails overcame this instinctive restraint, and great-horneds probably could, too.

The greater problem for the owls would be the nest one. They would have to find some existing nest to use, and we know which ones those might be. Now I really don't think great horned owls would go up to either the Trump Parc or 927 nests and expropriate them, as they are way above the tops of the trees. Great horned owls don't nest at those heights. But when I first learned of Pale Male, I said the same thing about red-tails. I was wrong for the urban red-tails, and I could be wrong for an emerging urban great horned owl population, too.

Finally, great-horneds are noted for nesting on just about any flat surface that has only a scattering of nest-like materials. In desperation, a pile of old leaves on the corner of a flat roof could work. If a pair of great horned owls is noted in Central Park for a winter, a platform tree nest could be erected, to see what happens.

All of this is speculation, with the new owl perhaps soon departing. But if it hangs around, another unanticipated chapter in Central Park raptors might emerge. As before, let's watch and see what happens.

--John A. Blakeman